Work-from-home dad Jonathan Haber, 51, is trying to complete a four-year philosophy degree in one year by taking a number of free Massively Open Online Courses (MOOCs).

Retired legal consultant Karen Phillips, 67, downloads five-minute videos from Khan Academy, an educational website that promises to teach “almost anything for free,” when life presents questions she can’t answer. And Cyrus Newitt, a 70-year-old lighting designer, says he had his “peak educational experience” last winter when he completed a free Coursera class featuring an eminent University of Virginia professor’s fireside chats on modern world history.

These avid online learners are just four boomers taking advantage of a movement that many, including Bill Gates, predict is education’s future. Ever since Cisco CEO John Chambers boldly predicted in the late 1990s that “education over the Internet is going to be so big, it’s going to make email usage look like a rounding error,” there’s been a proliferation of MOOCs like Coursera and vocational sites like Lynda.com.

What’s a MOOC?

If you haven’t noticed, a brave new world of online educational opportunities now exists online. In a recent Washington Post column, education reporter Dylan Matthews predicted MOOCs could be a “game changer” for higher education by eliminating the expense of brick-and-mortar classrooms and allowing professors to teach hundreds of thousands of students at a time.

Since its launch in April 2012, Coursera has attracted 4 million students from 196 countries by offering more than 400 courses from top-tier universities such as Stanford, MIT and Princeton — and it continues to attract some 7,000 new students every day.

Khan Academy, which is not technically a MOOC but offers free video classes that users can download and watch at any time, has delivered more than 260 million lessons during its six years in existence. Nearly half a million students from around the world have enrolled in courses through edX, Harvard and M.I.T.’s online offering with 27 university partners, and more than 730,000 have watched Udacity’s three- to five-minute educational YouTube videos. Book publishers like Penguin are hosting online writing workshops. Nearly 3 million clients pay $25 per month to access technology tutorials at Lynda.com. And at Codecademy, another tech site, students to learn to write code for free.

Boomers, the first generation to fully exploit higher education’s benefits, see online learning as a cheap, convenient and user-friendly way to keep their minds — and careers — sharp. Students such as Phillips and Pietrzyk, who like learning in quick, need-it-now bites, favor sites like Khan Academy and Lynda.com. Those who, like Haber and Newitt, prefer the structure, coursework and camaraderie of an actual college course tend to join international rosters of students to learn about computer science and engineering (and more) from some of the world’s best professors through MOOCs.

“These online courses open the doors to the universe,” says Newitt, who is deliberating which Coursera class to take this winter. “I feel like I’m part of the cutting edge. And for someone who sometimes worries that this stuff is passing him by, it’s great to be involved in a revolutionary educational system.”

“A lot of boomers who have been able to survive this difficult economy still find their jobs are not necessarily satisfying,” says Steve Poizner, who founded Empowered in partnership with UCLA and venture capitalists. “So they’re looking for an encore career.”

Lynda Weinman, 58, was aware of the need for affordable technology education when she created Lynda.com to teach software, creative and business skills. Users can learn about search engine optimization (SEO) or how to operate complex new software programs by downloading tutorials whenever they need them, without the boss or kids having to know. It’s quick, efficient and anonymous, which Weinman says is a key to her site’s success. “Everyone is afraid that everyone else knows how to do things and assumes somehow they should, too,” she says.

“Things change so quickly that keeping up with computer programs and graphic design could be a full-time job,” notes Pietrzyk, who downloads Lynda.com videos whenever she has a question about, say, the latest version of Wordpress or Photoshop. (Thanks to her multitasking and curiosity, she’s lost 25 pounds in the past two years.)

Phillips, on the other hand, downloads Khan Academy videos onto her iPad strictly for personal edification. She got her introduction to the site after a camping trip, when she looked up at the big night sky and could identify nothing but the moon. After watching a short astronomy lesson, she can now find the Big and Little Dippers.

Her personal interests have since led her to a class about the Hudson River School artists and, perhaps surprisingly, a course called “LeBron Asks,” featuring the Miami Heat forward’s series of videos that explains math and statistics through the lens of basketball. "Online learning is so much better than school ever was,” Phillips says.

Loving Learning with MOOCs

Grownups who miss the college experience are signing up for MOOCs with all the academic trimmings: class schedules, a syllabus, lectures and reading assignments. Haber feels fortunate to be able to “sit in the most gigantic of virtual classrooms” with thousands of other self-motivated recreational learners. Most MOOC students already have a college degree, he says, and they’re studying for the sheer joy of learning rather than trying to advance their careers.

“If you enroll in this kind of course, you’re not just listening to a bunch of lectures when you feel like it,” Haber says. “You have to take it seriously and set aside enough time to carefully listen to the lectures, pay attention, take notes and do all the readings and assignments.”

Many believe that MOOCs are revolutionizing higher education by offering the masses access to portals once reserved for those who could afford hefty tuition. The three major companies that provide free online learning — Coursera, Udacity, which focuses on technical education, and edX, which offers rigorous science, technology and humanities courses from the world’s best universities — are growing exponentially, even as traditional college enrollments are declining.

While MIT has been offering online lectures and course assignments through OpenCourseWare since 2002, MOOCs didn’t go viral until 2011, when 150,000 people signed up for Stanford University computer science professor Sebastian Thrun’s first online course.

Estimates of dropout rates for MOOCs vary widely, but expert observers agree they’re high. A good number of users sign up for the free courses but never check in. Some drop out when they realize the amount of work required. Some never planned to do the coursework but want to audit renowned professors. Recreational learners who aren’t using the courses to advance their careers or earn degrees see no harm in abandoning a course that doesn’t hold their interest.

“If you don’t like a course, you can simply drop out — and many people do,” Haber says. “You can cut corners and still pass. But why on earth would you do that? The reward is learning the material.” And, as many folks at midlife are already aware. Taking classes and learning new things has a value even beyond the "knowledge" acquired. It's a way to stay engaged and keep the brain stimulated, which is one of the best things we can do for our mental fitness.